1. Field of the Invention
The present invention relates to a device for measuring and scraping operations in the field of restorative dentistry and more particularly to an improved device for measuring an inclination angle of the tapered surface of a plaster die duplicated from the prepared tooth, said plaster die being mounted on a surveyor utilized in the "conus crown" telescope technology, and scraping a wax patter to be fabricated on the plaster die for partial denture as required.
2. Description of the Prior Art
To remedy drawbacks inherent to the conventional parallel telescope technology in the field of restorative dentistry Dr. Karlheinz Korber in West Germany developed a new technology that is called "conus crown" telescope technology about twenty years ago. This technology has been satisfactorily employed for partial denture and to practice the technology a device for measuring an inclination angle of the tapered surface of a plaster die which forms a part of a partially worked model mounted on a surveyor and scraping it to fabricate a tapered conical crown according to a calculated inclination angle (hereinafter referred to simply as device) was specially designed and fabricated by Dr. Korber. His device was simple in structure but it was found that it had a few problems. One of them is that the device has a long length and thereby it occuplies a wide space on the table of the surveyor. Another problem is that after a tool on the device is inclined due to contact with the tapered surface of a wax pattern, a measured inclination angle is indicated with less accuracy, because an indicator is designed in such a manner that an indicating needle is made integral with the tool and it is actuated by turning about a junction point between the tool and the needle in the lever fashion.
In view of the first mentioned drawback of the conventional device Dr. Korber made an improvement so as to reduce the length of the device. The improvement was made such that an indication needle was oriented in the lateral direction at a right angle relative to the tool but no improvement was achieved with respect to accuracy of measurement. Moreover, it was found that measuring and scraping operations were carried out with much difficulties due to the existence of the transversely extending indicating needle.